In an apparatus intended for cleaning air in a room for the purpose of dust-collecting, deodorizing, sterilizing, etc., not only efficiency but largeness of volume of treated air is required. As the volume of the treated air is increased, the air in a room can be circulated to a larger degree, thereby cleaning the air in a room as a whole within a shorter period of time. Even if an apparatus itself is efficient, if the apparatus is put in a room the volume of which is beyond the possible treating capacity of the apparatus, the circulation of the air within the room may not be fully effected, thereby requiring a longer time to clean the whole air in the room.
Recently, sterilization and deodorization using ozone has been highlighted. However, since ozone is harmful to the human body, such an apparatus must have an ozone removing means before exhausting the treated air. Conventional systems employ layers of activated carbon or catalyzers provided in the air passage to remove ozone, thus giving rise to a larger pressure drop (loss) at those layers. The resultant drawbacks are:
(1) Since the air in a room may not be stirred, the effect of dust-collecting, deodorization and sterilization is concentrated in the vicinity of the apparatus. Consequently, such an apparatus is not suitable to be used in a spacious room. PA1 (2) The types of available fans are limited. For example, cross flow fans which are capable of generating large quantity of air flow with a relatively low noise may not be used. PA1 (3) If the thickness of the layers for removing ozone is reduced to lessen the pressure drop, ozone removal may not be fully effected. PA1 (4) Therefore, the apparatus inevitably becomes large in size in order to remove ozone completely and to increase the amount of the treated air.